1. Field of the Invention
The invention relates to a storage/dispensing system for a flowable dental substance, in particular for storing and dispensing small quantities of dental substances with an elevated content of highly volatile solvents, such as flowable dental adhesives, fluoride varnishes, liners or desensitisers. The invention furthermore relates to a storage/dispensing/application system for a flowable dental substance and to a dental system and to a method for the application of a flowable dental substance.
2. Description of the Related Art
In dentistry, dental adhesive materials, varnishes or desensitisers are often formulated on the basis of organic solvents such as for example acetone, ethyl acetate, ethanol or propanol. The organic solvents sometimes also act as diluents and/or suspending agents. The organic solvents exhibit an elevated vapour pressure. Containers which are capable of providing stable storage for these solvents over an extended period are generally made from solvent-tight films which comprise at least one diffusion-proof barrier layer, such that gas diffusion, in particular of organic solvents such as acetone, ethyl acetate, ethanol and propanol, is suppressed and the composition of the flowable dental substance undergoes no change. An aluminium laminate film is generally used as the barrier layer which, due to the effective barrier action of the metallic layer, ensures that there is no diffusion loss of liquid constituents. The laminate film additionally provides protection from light for any photosensitive substances possibly present in the dental material (the flowable dental substance).
Various systems for the storage and metered application of small quantities of dental materials are known. EP 0 895 943, WO 98/23220, EP 0 770 021, DE 31 22 237 and DE 298 14 215, for example, disclose various “single-dose” devices, some of which may contain small quantities of dental material and comprise an integral application tool on a storage vessel in such a manner that, for example, when the tool is simply pressed into the container, the tool is wetted with the predosed dental material which is to be applied, so permitting straightforward single use. Storage and application devices are furthermore known in which the device itself comprises no integral application tool, for example from EP 1 153 579. The stated devices are both simple to operate and hygienic to use, but are disposable articles. Multiple-use articles which may be used repeatedly are more resource-efficient, in particular with regard to packaging materials, which is desirable in times of increased environmental awareness.
In the dental materials sector, DE 197 13 951 discloses a container/dropper system for dental adhesive which serves as a multiple-use container for the storage and application of a dental adhesive which is dissolved in acetone or ethyl acetate and is polymerisable with visible light. DE 197 13 951 proposes a resiliently deformable plastics bottle with a dropper insert which is rendered diffusion-proof with regard to volatile solvents by using laminate layers and which is capable of supplying a controlled quantity of the dental material. Colouring of the bottle wall additionally makes the container opaque to visible light. One possible structure of the container wall is known, for example, from WO 98/31742. With the aim of controlling the dropping speed of low viscosity liquids, DE 197 13 951 proposes using a dropper insert with a dropper channel which widens from the inside outwards, wherein the diameter at the discharge end corresponds to the desired drop size and the diameter at the inlet end is within a range between 0.1 and 0.25 mm and determines the flow rate of the dental material. It is to be assumed that the design principle underlying this bottle and the configuration of the dropper channel is that pressure builds up within the bottle after resilient deformation thereof, which pressure drives the liquid through the small opening at the inlet end into the dropper channel. Due to the widening channel, the volume available for the upwardly moving liquid increases, the liquid then being under virtually no pressure. When the bottle is upended, gravity enables the liquid to overcome the capillary forces and surface tension which are retaining it in the dropper channel and the liquid leaves the channel dropwise.
A dropper channel whose diameter is greater at the inlet end than the diameter at the discharge end is also disclosed in EP 0 431 885, U.S. Pat. No. 5,221,017 and U.S. Pat. No. 6,129,248.
When applying a dental material, a dentist is generally anxious to ensure that the dental material is applied onto the patient's tooth as quickly as possible using an application instrument, for example a microbrush. If the dropper channel is of a shape which widens from the inside outwards, as in the known devices just described above, the head of a microbrush which is introduced into the channel will seal it so effectively that discharge of the material is no longer possible. Furthermore, the insertion of a brush head into the channel may deform the channel in such a manner that dispensing characteristics are modified. There is furthermore a risk that when the brush is inserted into the channel, the bristles located on the side of the brush will bend, which would impair the proper functioning of the brush.
Another configuration of the dropper channel, namely a dropper channel which tapers in towards the discharge end, is known from U.S. Pat. No. 6,223,947. However, direct discharge of the dental material onto an application instrument proves difficult in this case.